transmet/news/news.go

package news

import (
    "time"
    "database/sql"	
	_ "github.com/lib/pq"
	"fmt"
	"github.com/dballard/transmet/categories"

)

type News struct {
    news_id int
    Url		string
    Title	string
    Category_id	int
    Date	time.Time	
    Notes	string
    Expoerted bool
}

/* Storage Node containing:
 *  Name - categry name
 *  News children
 *  Category - category of this node
 *  Children - sub containers: mapped to sub categories
 */ 
type NewsContainer struct {
    Name string
    News []News
    Category *categories.Category
    Children map[int]*NewsContainer
}

// Insert News item into DB
func (news *News) Insert(db *sql.DB) error {
    _, err := db.Exec("INSERT INTO news (url, title, category_id, notes) VALUES($1, $2, $3, $4)", news.Url, news.Title, news.Category_id, news.Notes );
    if err != nil {
        fmt.Println("Error inserting news: ", err)
        return err
    }
    return nil
}

func nullStringToString(str *sql.NullString) string {
    if str.Valid {
        return str.String
    } else {
        return ""
    }
}

// Init and add a news container to the Data Structs
func addContainer(category_id int, flat, tree map[int]*NewsContainer) {
    container := &NewsContainer{ Category: categories.CategoriesFlat[category_id], Name: categories.CategoriesFlat[category_id].Name, News: []News{}, Children: map[int]*NewsContainer{} }
    flat[category_id] = container
    parent := categories.CategoriesFlat[category_id].Parent
    if parent.Valid {
		if _, ok := flat[int(parent.Int64)]; !ok {
		    addContainer(int(parent.Int64), flat, tree)
		}
		flat[int(parent.Int64)].Children[category_id] = container
    } else {
        tree[category_id] = container
    }
}

// Load and return in NewsContainer format all the unexported news items
func LoadPage(db *sql.DB, offset, amount int) ([]News, int, error) {
    categories.LoadCategories(db) // required by addContainer

	rows, err := db.Query("SELECT url, title, category_id, timestamp, notes FROM news WHERE exported is null order by timestamp DESC")
	if err != nil {
		fmt.Println("DB errpr reading LoadPage news: ", err)
		return nil, 0, err
	}
	defer rows.Close()

	return convertSqlToNews(rows)
}

// Load and return in NewsContainer format all the unexported news items
func Unexported(db *sql.DB) (map[int]*NewsContainer, int, error) {
    categories.LoadCategories(db) // required by addContainer

	rows, err := db.Query("SELECT url, title, category_id, timestamp, notes FROM news WHERE exported is null order by category_id ASC")
	if err != nil {
		fmt.Println("DB errpr reading unexported news: ", err)
		return nil, 0, err
	}
	defer rows.Close()
	
	return convertSqlToNewsContainer(rows)
}	

func convertSqlToNews(rows *sql.Rows) ([]News, int, error) {
	news := []News{}
	count := 0
	for rows.Next() {
	    newsItem := News{}
	    var url, title, notes sql.NullString 
	    var category_id sql.NullInt64
	    err := rows.Scan(&url, &title, &category_id, &newsItem.Date, &notes)
	    if err != nil {
	        fmt.Println("Error reading news from DB: " + err.Error())
	        return nil, 0, err
	    }
	    
	    newsItem.Url = nullStringToString(&url)
	    newsItem.Title = nullStringToString(&title)
	    newsItem.Notes = nullStringToString(&notes)
	    	    
	    if category_id.Valid {
	        newsItem.Category_id = int(category_id.Int64)
	    } else {
	        continue  // needs a category id
	    }
	    
	    
	    news = append(news, newsItem)
	    count++
	}
	
	return news, count, nil
}
	
func convertSqlToNewsContainer(rows *sql.Rows) (map[int]*NewsContainer, int, error) {
	newsTree := map[int]*NewsContainer{}
	newsFlat := map[int]*NewsContainer{}
	count := 0
	for rows.Next() {
	    news := News{}
	    var url, title, notes sql.NullString 
	    var category_id sql.NullInt64
	    err := rows.Scan(&url, &title, &category_id, &news.Date, &notes)
	    if err != nil {
	        fmt.Println("Error reading news from DB: " + err.Error())
	        return nil, 0, err
	    }
	    
	    news.Url = nullStringToString(&url)
	    news.Title = nullStringToString(&title)
	    news.Notes = nullStringToString(&notes)
	    
	    if category_id.Valid {
	        news.Category_id = int(category_id.Int64)
	    } else {
	        continue  // needs a category id
	    }
	    
	    if _, ok := newsFlat[news.Category_id]; !ok {
	       addContainer(news.Category_id, newsFlat, newsTree)
	    } 
	    container := newsFlat[news.Category_id]
	    container.News = append(container.News, news)
	    count++
	}
	
	return newsTree, count, nil
}

// Helper fn - formating - math 
func (this *NewsContainer) HeaderDepth(start int) int {
    return start + this.Category.Depth()
}

// Mark the current batch (news.exported is null) as exported in this batch (exported = now())
func MarkExported(db *sql.DB) error {
    now := time.Now()
    
    _, err := db.Exec("UPDATE news SET exported=$1 WHERE exported is null", now)
    if err != nil {
        fmt.Println("DB errror: news.MarkExported():", err)
    }
    return err
}